Quantifying The Relationship Between Urbanization And Eco-environment In The Urban Agglomeration In The Middle Reaches Of Yangtze River

The coordinated development of urbanization and eco-environment is the foundation for the steady progress of a city and the even whole region.In recent years,many unreasonable human activities have made the contradiction between urbanization and eco-environment increasingly prominent.Therefore,it is urgent to carry out research on the relationship between them.As the main form of China's new-type urbanization,urban agglomerations play a vital role in the country's economic and social development.However,existing literature engaging in the task of studying the relationship between urbanization and eco-environment from the perspective of urban agglomeration is limited.Therefore,based on the panel data from 2000 to 2015,this paper quantified the relationship between urbanization and eco-environment in the urban agglomeration in the middle reaches of Yangtze River.Firstly,according to the principle of index selection and the actual situation of the study area,the comprehensive evaluation index systems of urbanization and eco-environment were established.The entropy method was used to calculate the comprehensive development level of urbanization and eco-environment in 31 cities of the study area for 16 years.Secondly,based on the coupling coordination model,the level,type,stage and spatial-temporal characteristics of the coupling coordinated development of urbanization and eco-environment were studied.Finally,the panel data model in econometrics was used to further study the effects of urbanization on the eco-environment.Main conclusions are as follows:(1)The urbanization had entered a period of rapid development in the study area.The urbanization was centered on Wuhan,Changsha and Nanchang with decreasing outwards as “triangle” shape.The radiation capability of provincial capitals had increased year by year,and the connection among cities had enhanced.The multi-polar with multi-node and multi-center development pattern had been formed.The eco-environmental quality of most cities increased in the first five years,and remained stable in the last five years.In the study area,it was Poyang Lake Economic Zone> Ring of Changsha-Zhuzhou-Xiangtan Urban Agglomeration> Wuhan Metropolitan Area.The eco-environmental quality of Wuhan Metropolitan Area had formed a “central-periphery” pattern with Wuhan City as the center.The spatial distribution of the eco-environmental quality of the Ring of Changsha-Zhuzhou-Xiangtan Urban Agglomeration had obvious dual characteristics.It was the eastern region > the western region in the first five years,the northern region > the southern region in the last ten years.The eco-environmental quality of the Poyang Lake urban agglomeration was relatively stable.(2)From 2000 to 2015,the coordinated development level of urbanization and eco-environment was constantly increasing with spatial imbalance and spatial heterogeneity.The coupling degree showed a "ladder pattern" in the four years,that was,the southeast region <the central region <the northwest region.The coupling coordination degree revealed a “triangle” spatial pattern,which gradually decreases from the provincial capitals.To gradually reduce or even eliminate the gap between the southeast-northwest and the center-periphery of the study area,it must give full play to the radiating role of the three major cities.We also should promote regional sustainable development in order to make urbanization and eco-environment become more and more coordinated.The coupling coordination degree had obvious spatial positive correlation,and the correlated degree was continuously strengthened.The two systems showed strong spatial dependence.The agglomeration type of coupling coordination degree in space is constantly changing.From the changes of more than ten years,it can be seen that the spatial difference between urbanization and eco-environment of the study area is gradually narrowing and the spatial pattern is gradually clear.(3)The eco-environment of the study area and its four sub-areas showed an asymmetrical inverted U-curve trend which first increased and then decreased with the increase of urbanization.The urbanization rate corresponding to the inflection point of the inverted U-curve in the Wuhan Metropolitan Area was the highest compared with the other three sub-areas.So the Wuhan Metropolitan Area may have a higher urbanization rate when formulating the regional planning to ensure a healthy development of the eco-environmental quality.Cities such as Wuhan,Ezhou and Huangshi have reached this inflection point in 2015.These cities should pay attention to the protection of the eco-environment.Improvements in both industrial structure and infrastructure intensity have a positive effect on the eco-environment of the study area.The urbanization rate of urbanization factors had the strongest impact on the eco-environment.There were significant spatial differences in the impact of urbanization rate on the eco-environment,that was,Wuhan Urban Agglomeration > Xiangyang-Jingmen-Yichang Urban Agglomeration > Ring of Changsha-Zhuzhou-Xiangtan Urban Agglomeration > Poyang Lake Economic Zone.The eco-environmental quality of Wuhan,Changsha,Ezhou,Huangshi and Yichang decreased with the increase of urbanization rate.The urbanization rate of Wuhan had the greatest impact on the eco-environment.